Upgradeability Checks

[HashHaran]

As you know there are certain caveats to writing upgradable contracts in solidity. For example:

• No constructor in the implementation contract unless it neither reads nor writes to storage
• Types of already declared state variables in previous versions of the implementation cannot change etc. Check here for a more extensive list.

I am not sure if all such checks can be performed in solidity. Opening the issue here for discussion.